<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="js/jquery-3.3.1.min.js"></script>
    <script>
        $(function(){
            // 将DOM对象转换为jQuery对象
            var objDom = document.getElementById('hello')

            var objJquery = $(objDom)
            console.log(objJquery.text())
            objJquery.css('color', 'red')

            // 将jQuery对象转换为DOM对象
            var obj1 = $('#world')

            // var obj2 = obj1[0]
            var obj2 = obj1.get(0)
            console.log(obj2.innerText)
        })
    </script>
</head>
<body>
    <div id="hello">哈哈</div>

    <p id="world">嘻嘻</p>
</body>
</html>